This invention is directed to a dishwashing composition, and a method for improving starchy soil removal and preventing starch build-up on articles being cleaned. More particularly, the invention is directed to a superior dishwashing composition that has a silicon-comprising surfactant, a dialkyl ester of an alpha, omega-alkyl dicarboxylic acid surfactant wherein the alkyl chain of the dicarboxylic acid is functionalized with at least one hydrophilic group, or both. The dishwashing composition unexpectedly results in dishware that does display improved starchy soil removal and does not display starch build-up after multiple washing cycles.
Traditional industrial and domestic dishwashing systems rely on a combination of high alkalinity detergent washes and chlorine bleach for cleaning and sanitizing dishware. Such systems perform well on bleachable stains; however, they tend to be deficient in removing starchy soils like those often found on dishware in domestic kitchens, hospitals, cafeterias, catering industries and the like.
Other attempts have been made to create dishwashing systems that are effective at handling starchy soils. These systems typically employ commercially available enzymes that break down the starchy soil in the various cycles of the dishwashing systems they are employed in. The enzymes used in systems for treating starchy soils on dishware are generally not limited and include those that typically break or hydrolyze the xcex1-1,4-glycosidic linkages of the starch backbone.
In addition to being sanitized, it is very desirable for dishware exiting dishwashing systems to be dry with a glossy finish. These characteristics are often achieved by employing a rinse aid composition in the final rinse step of the dishwashing system.
Unfortunately, however, it has been discovered that conventional rinse aid and detergent washes typically result in dishware with non-appealing characteristics. This is true because conventional detergent washes are not always effective at removing starchy soils from the dishware they are employed to clean. Also, studies indicate that conventional rinse aid compositions can result in poor starch removal on dishware subject to as little as one cleaning cycle.
It is of increasing interest to develop dishwashing compositions that maintain their conventional characteristics and do not adversely interfere with the cleaning process of a dishwashing system. Also, it is of increasing interest to develop methods that induce starchy soil removal and prevent starch build-up on articles, such as dishware, being cleaned. The inventions described herein, therefore, are directed to a superior dishwashing composition, and a method for improving starchy soil removal and preventing starch build-up on articles. Such inventions are achieved by employing a dishwashing composition that has a silicon-comprising surfactant, a dialkyl ester of an alpha, omega-alkyl dicarboxylic acid surfactant wherein the alkyl chain of the dicarboxylic acid is functionalized with at least one hydrophilic group, or both.
Methods have been disclosed for cleaning plasticware. In U.S. Pat. No. 5,603,776, plasticware is cleaned by subjecting the same to an alkaline aqueous cleaning agent and an aqueous rinse comprising nonionic surfactant, fluorinated hydrocarbon surfactant and polyalkylene oxide-modified polydimethylsiloxane.
Further, rinse aid compositions that comprise a modified polydimethylsiloxane have been disclosed. In U.S. Pat. No. 5,880,089, a rinse aid composition with a modified polydimethylsiloxane or a polybetaine-modified polysiloxane, a fluorinated hydrocarbon nonionic surfactant and a nonionic block copolymer of ethylene oxide and propylene oxide is disclosed.
Still further, in U.S. Pat. No. 5,880,088, rinse aid compositions that comprise a polyether or polybetaine polysiloxane copolymer, hydrotrope and nonionic block copolymer of ethylene oxide and propylene oxide are disclosed.
Also, in WO 98/30662, a detergent composition with a source of alkalinity and a blend of nonionic alkoxylated surfactant and nonionic alkoxylated silicone surfactant is described.
The prevention of, for example, starchy soil build-up, and starchy soil removal on articles being cleaned has not been addressed in the above described-references. The present inventions, therefore, are patentably distinguishable from the above-described since, among other reasons, they are directed to starchy soil removal and the prevention of starch build-up on articles being cleaned, particularly in a dishwashing system. Moreover, the present inventions display superior results without requiring the use of polybetaine modified polysiloxanes; fluorinated hydrocarbons; sorbitan fatty acid esters; nonionic, non-silicone comprising alkoxylated surfactants; and nonionic block copolymers of ethylene oxide and propylene oxide. Particularly, a nonionic surfactant with an ethylene oxide group is not required when the silicon comprising surfactant is nonionic.
In a first embodiment, the invention is directed to a dishwashing composition comprising:
at least one member selected from the group consisting of a silicon comprising surfactant and a dialkyl ester of an alpha, omega-alkyl dicarboxylic acid surfactant wherein the alkyl chain of the dicarboxylic acid is functionalized with at least one hydrophilic group, or both wherein the dishwashing composition prevents starch build-up and improves soil removal on articles being washed.
In a second embodiment, the invention is directed to a method for using the dishwashing composition described in the first embodiment of this invention.
In a third embodiment, the invention is directed to an optional pre-coating composition that enhances soil removal and prevents starch build-up on articles being cleaned, the pre-coating composition comprising at least one member selected from the group consisting of a silicon comprising surfactant and a dialkyl ester of an alpha, omega-alkyl dicarboxylic acid surfactant wherein the alkyl chain of the dicarboxylic acid is functionalized with at least one hydrophilic group.
As used herein, dishwashing composition is defined to mean a detergent wash or a rinse aid that may be used in a domestic or industrial dishwashing machine, the detergent wash or rinse aid being a block, tablet, powder, gel or liquid prior to being introduced to the dishwashing system. Also, the silicon comprising surfactant and the dialkyl ester of an alpha, omega-alkyl dicarboxylic acid surfactant that may be used in the dishwashing composition of this invention may herein be referred to as the soil removal surfactants.
There generally is no limitation with respect to the silicon comprising surfactant and the dialkyl ester of an alpha, omega-alkyl dicarboxylic acid surfactant that may be used in this invention other than that the surfactants may be employed in a dishwashing composition.
Such silicon comprising surfactants are typically siloxanes. The preferred siloxane which may be used in this invention is one having the formula: 
wherein each A is independently a hydrocarbon bridging group; each R is independently a C1-10 alkyl, aryl, cationic group, anionic group, polyalkylene oxide; x is an integer from about 1 to about 250; and each m is 0 or 1, with the proviso that at least one R group is hydrophilic and when R is hydrophilic m is 1.
Typical cationic groups include ammonium, quaternary nitrogen, imidazoline and pyridinium compounds. Typical anionic groups include a sulfate, sulfonate and carboxylate.
The preferred alkyl used in this invention is a methyl, and the preferred polyalkylene oxide is an ethoxylate, propoxylate or copolymer prepared therefrom. The preferred hydrocarbon bridging groups that may be used in this invention include at least one having the formula: 
wherein d is an integer from about 1 to about 10.
The molecular weight of the silicon comprising surfactants that may be used in this invention is typically from about 250 to about 200,000, preferably, from about 300 to about 150,000, and most preferably, from about 500 to about 100,000, including all ranges subsumed therein.
The silicon comprising surfactants which may be used in this invention can be made for example, by equilibration of the appropriate portions of end capped and monomer units according to the reaction: MM+Dxxe2x86x92MDxM. Such a reaction is generally known as an equilibration reaction, and is catalyzed by an acid or a base. Similar reactions are depicted in Silicone Surfactants, as edited by Randal Hill, Marcel Dekker (Vol. 86 1999), the disclosure of which is incorporated herein by reference. Other similar descriptions of the synthesis of similar surfactants may be found in U.S. Pat. Nos. 3,931,047 and 5,410,007, the disclosures of which are incorporated herein by reference. Such surfactants are often commercially available by Witco Corporation, Goldschmidt Chemical Corporation and the Dow Corning Corporation.
The most preferred silicon comprising surfactants used in this invention are those which are sold by Witco Corporation under the name Silwet L-77, L-7600, L-7602, L-7604 and L-7210.
The dialkyl ester of an alpha, omega-alkyl dicarboxylic acid surfactant which may be used in this invention is one which has the formula: 
wherein each R1 is independently a C1-10 alkyl; each R2 is independently a hydrogen, C1-10 alkyl or aryl; G is a hydrophilic group wherein the hydrophilic group is a cationic group selected from the group consisting of an ammonium, quaternary nitrogen, imidazoline or pyridinium compound, or an anionic group selected from the group consisting of a sulfate, sulfonate, phosphate and carboxylate, and z is an integer from about 1 to about 15.
Such surfactants are typically made by the methods described in U.S. Pat. Nos. 2,028,091 and 2,176,423, the disclosures of which are incorporated herein by reference. The preferred surfactant in this category is Aerosol OT (sulfobutanedioic acid 1,4-bis-(2-ethylhexyl) ester sodium salt) as made commercially available by Cytec Industries, Inc.
Where applicable, the counter ions that may be used in this invention include, for example, Brxe2x88x92, Ixe2x88x92, Clxe2x88x92, SO42xe2x88x92, OHxe2x88x92, HSO4xe2x88x92, alkali metal, alkaline earth metal, NH4+ and the like.
When the dishwashing composition used with the soil removal surfactants of this invention is a detergent wash, such a wash typically comprises at least one compound capable of causing starch degradation. The compound which is capable of causing starch degradation is only limited to the extent that it is a compound which is capable of hydrolyzing the glycosidic linkages of starch or breaking any of the Sp3 bonds of the glucose monomer that make up the starch backbone. Typically, the compounds which are used for starch degradation in the detergent washes which may be employed in this invention are generally classified as enzymes, caustic agents and oxidizing agents, whereby the oxidizing agents may be used with catalysts. The enzymes which may be used for starch degradation in the detergent wash is used in this invention include xcex1-amylase enzymes such as those made commercially available from Novo Nordisk and Genencor and sold, for example, under the names of Termamyl(copyright), Duramyl(copyright) and Purastar OxAm. When the detergent wash is prepared with an enzyme, such as amylase, the amount of enzyme typically used in a formulation is such that the final use composition of said enzyme component has an enzyme activity from about 10 to about 108 maltose units (MU) per kilogram, and preferably from about 102 to about 106 MU per kilogram, and preferably, from about 102 to about 104 MU per kilogram. The enzyme activity as referred to herein can be determined by the method as described by P. Bernfeld, xe2x80x9cMethod of Enzymologyxe2x80x9d, Vol. 1 (1955), page 149, the disclosure of which is incorporated herein by reference. Other additives which may be employed in the enzymatic detergent washes which may be used in this invention include disilicates, such as sodium disilicate, soda ash, triphosphates like sodium triphosphates, chelators like nitriloacetic acid, polycarboxyates such as sodium polycarboxylate, water, fatty acid alkoxylates and alcohol phosphate ester-type defoaming agents. A more detailed description of the detergent washes (which comprise enzymes) that may be used in this invention are described in U.S. Pat. Nos. 5,695,575, 5,741,767 and 5,877,134, the disclosures of which are incorporated herein by reference.
Detergent washes using caustic (e.g., NaOH, KOH) that may be used with the soil removal surfactant(s) of this invention are known and described in U.S. Pat. No. 4,774,014, the disclosure of which is incorporated herein by reference. Typically, such detergent washes comprise from about 10% to about 75% by weight caustic, based on total weight of the detergent wash and including all ranges subsumed therein.
The detergent washes that utilize oxidizing agents that may employ the soil removal surfactants described in this invention include washes with hydrogen peroxide, chlorine bleach and organo peroxyacids. Such washes are described in U.S. Pat. No. 5,741,767, the disclosure of which is incorporated herein by reference.
The catalysts which may be used in the detergent washes that may employ the soil removal surfactant described in this invention include those which may be broadly classified as metal containing catalysts that enhance oxidizing agents in breaking Sp3 bonds of a glucose ring. Illustrative examples of the preferred metal containing catalysts include those comprising manganese, iron, cobalt, titanium, molybdenum, nickel, chronium, copper, ruthenium, tungsten, silver and mixtures thereof. A more detailed description of such catalysts may be found in commonly assigned patent application, U.S. Ser. No. 09/344,013, the disclosure of which is incorporated herein by reference.
When the dishwashing composition of this invention is a rinse aid (which comprises the soil removal surfactant of this invention), conventional rinse aid additives may be used, including hydroxy acids, alcohols, hydrotropes, preservatives and water. The hydroxy acids which may be employed in the rinse aid of this invention include those that are naturally occurring and commercially available. Often, when preparing the rinse aid compositions of this invention, about 0.0% to about 50.0%, and preferably, from about 5.0% to about 40.0%, and most preferably, from about 10.0% to about 30.0% by weight of hydroxy acid is employed based on total weight of the rinse aid composition, including all ranges subsumed therein. An illustrative list of the hydroxy acids which may be used in this invention include malic acid, lactic acid, citric acid, glycolic acid, tartaric acid and the like. Citric acid, however, is often the most preferred hydroxy acid.
The alcohols which may be employed in this invention include, for example, C1-C8 primary, secondary or tertiary alcohols. Such alcohols are commercially available. Isopropanol, however, is often the most preferred alcohol. When alcohols are employed in rinse aid compositions, the rinse aid compositions often employ from about 0.0% to about 20.0%, and preferably from about 0.5% to about 10.0% and most preferably from about 1.0% to about 5.0% by weight alcohol based on total weight of the rinse aid composition.
The hydrotropes which may be employed in this invention are limited only to the extent that they enhance the solubility of the surfactants in the rinse aid composition of this invention. The hydrotropes which may be used in this invention are those which are commercially available, and an illustrative list includes sodium xylene sulfonate, sodium cumene sulfonate, hexylene glycol, propylene glycol, dihexyl sodium sulfonate and low molecular weight sulfates. Other useful hydrotropes which may be employed in this invention include those described in U.S. Pat. Nos. 3,563,901 and 4,443,270, the disclosures of which are incorporated herein by reference.
When hydrotropes are employed in the rinse aid composition of this invention, they often represent from about 0.1% to about 20.0%, and preferably, from about 2.0% to about 15.0%, and most preferably, from about 5.0% to about 12.0% by weight of the total weight of the rinse aid composition, including all ranges subsumed therein.
The preservatives which may be used in the rinse aid composition of this invention include ascorbic acid, erythorbic acid, sorbic acid, thiodipropionic acid, ascorbyl palmitate, butylated hydroxyamisol, butylated hydroxytoluene, calcium ascorbate, calcium sorbate, dilauryl thiodipropionate, potassium bisulfate, potassium metabisulfate, potassium sorbate, sodium ascorbate, sodium bisulfate, sodium meta bisulfite, sodium sorbate, sodium sulfite, sulfur dioxide, tocophenols and Group IA and IIA salts, with potassium chloride being preferred. When preservatives are used in the rinse aid composition of this invention, they typically make up about 0.01% to about 0.2%, and preferably, from about 0.02% to about 0.1%, and most preferably, from about 0.04% to about 0.8% by weight of the total rinse aid composition, including all ranges subsumed therein.
When water is employed in the dishwashing composition of this invention, it generally is the solvent making up the balance of the composition.
The dishwashing composition of this invention may be prepared via any of the art recognized techniques. Essentially, the components (e.g., surfactant, water) of the composition are, for example, mixed, stirred or agitated. The detergent composition of this invention may be made at ambient temperature, atmospheric pressure or at any pressure or temperature variations which may result in the detergent compositions of this invention. The addition of the components is not limited to any particular order, with the proviso that the resulting composition is one which may be employed as a detergent composition that prevents starch build-up in cleaning systems.
The amount of soil removal surfactant employed in the dishwashing composition (i.e., detergent wash or rinse aid or both) of this invention is limited only to the extent that the amount employed results in improved starchy soil removal.
Typically, from about 0.5% to about 30.0%, and preferably, from about 0.75% to about 10.0%, and most preferably, from about 1.0% to about 2.0% of the dishwashing composition is soil removal surfactant, based on total weight of the dishwashing composition, including all ranges subsumed therein.
When conducting the method for preventing starch build-up on dishware in this invention, the method comprises the steps of:
a) contacting dishware soiled with starch with the dishwashing composition of this invention; and
b) removing the dishware from the dishwashing composition.
When conducting the method of this invention, the dishware being cleaned (e.g., knives, pots, pans, forks, spoons, glasses, mugs, cups, china, dishes or plastic kitchen utensils) in, for example, a dishwasher, is often subjected to at least one cycle selected from the group consisting of a presoak cycle, a wash cycle and a rinse cycle, followed by a final rinse cycle.
When the wash cycle utilizes the dishwashing composition of this invention (e.g., detergent wash), the wash cycle is typically run from about 5.0 seconds to about 15 minutes, and preferably, from about 10 seconds to about 12 minutes, and most preferably, from about 30 seconds to about 10 minutes in an industrial system, including all ranges subsumed therein.
In a domestic system, the wash cycle is typically run from about 2 minutes to about 45 minutes, and preferably, from about 5 minutes to about 35 minutes, and most preferably, from about 8 minutes to about 30 minutes, including all ranges subsumed therein.
The final rinse cycle when using the dishwashing composition (e.g., rinse aid) of this invention is typically run for about 5 to about 90 seconds in industrial systems and for about 2 minutes to about 25 minutes in domestic systems, and preferably, for about 10 seconds to about 60 seconds in industrial systems and about 5 minutes to about 20 minutes in domestic systems, and most preferably, from about 7 seconds to about 12 seconds in industrial systems and from about 10 minutes to about 15 minutes in domestic systems, including all ranges subsumed therein.
The temperature of the wash cycle (in industrial and domestic systems) is typically from about ambient to about 80xc2x0 C., and preferably from about 35xc2x0 C. to about 70xc2x0 C., and most preferably from about 55xc2x0 C. to about 65xc2x0 C., including all ranges subsumed therein. The temperature of the final rinse is usually from about ambient to about 95xc2x0 C., and preferably, from about 30xc2x0 C. to about 85xc2x0 C., and most preferably, from about 40xc2x0 C. to about 75xc2x0 C., including all ranges subsumed therein, whereby the dishware being cleaned is typically dipped in and/or sprayed with the dishwashing composition of this invention. The final result of such a method is clean dishware with a glossy finish, whereby starch removal has been enhanced and starch build-up has been prevented, and the dishware dries in about substantially the same time as clean dishware that has not been subjected to the detergent composition of this invention but has been subjected to a commercially available compositions.
As to the dishwashers, for example, that are used with the method of this invention, such dishwashers include those which are made commercially available from manufacturers including KitchenAid, Bendix Appliances, Electrolux, Meiko, Hobart, Winterhalter, Equator Appliance, Frigidaire, Asko USA and the like.
It is noted herein, that the soil removal surfactant described in this invention may be present in or dosed in the detergent wash or the rinse aid or both during the cleaning method. Moreover, the dishware cleaned via this invention (or cleaned via any conventional process) may be pretreated, prior to being subjected to soil, with a pre-coating composition. The pre-coating composition comprises:
(a) a silicon comprising surfactant, or
(b) an alpha, omega-alkyl dicarboxylic acid surfactant wherein the alkyl chain of the dicarboxylic acid is functionalized with at least one hydrophilic group, or
both.
The pre-coating composition may further comprise water, and typically consists of surfactant, and preferably, consists essentially of water and surfactant.
When water is present, the pre-coating composition typically comprises from about 8.0 ppm to about 9.9xc3x97105 ppm surfactant, and preferably, from about 10 ppm to about 500 ppm surfactant, and most preferably, from about 20 ppm to about 150 ppm surfactant.
The pre-coating composition may be applied to the dishware being cleaned via any art recognized technique. Typically, the dishware is dipped or sprayed with the optional pre-coating composition.
The amount of optional pre-coating composition applied is only limited to the extent that the pre-coating composition coats the surface of the dishware and does not interfere with the dishware""s conventional use.